CVE-2024-40900: cachefiles: remove requests from xarray during flushing requests

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-07-12 · updated 2026-08-04
Weakness: CWE-416

Description

In the Linux kernel, the following vulnerability has been resolved: cachefiles: remove requests from xarray during flushing requests Even with CACHEFILES_DEAD set, we can still read the requests, so in the following concurrency the request may be used after it has been freed: mount | daemon_thread1 | daemon_thread2 ------------------------------------------------------------ cachefiles_ondemand_init_object cachefiles_ondemand_send_req REQ_A = kzalloc(sizeof(*req) + data_len) wait_for_completion(&REQ_A->done) cachefiles_daemon_read cachefiles_ondemand_daemon_read // close dev fd cachefiles_flush_reqs complete(&REQ_A->done) kfree(REQ_A) xa_lock(&cache->reqs); cachefiles_ondemand_select_req req->msg.opcode != CACHEFILES_OP_READ // req use-after-free !!! xa_unlock(&cache->reqs); xa_destroy(&cache->reqs) Hence remove requests from cache->reqs when flushing them to avoid accessing freed requests.

Affected products

Linux kernel: from 5.19 before 6.1.95; from 6.2 before 6.6.35; from 6.7 before 6.9.6; 6.10-rc1, 6.10-rc2, 6.10-rc3 — fixed in 6.1.95, 6.6.35, 6.9.6

How to fix

Upgrade to a fixed version: Linux kernel 6.1.95, 6.6.35, 6.9.6. Check the vendor advisory for mitigations.

References

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